When I dropped mine off the the tech could not verify the rattle. But I was already prepared. I knew exactly what conditions I could reliably replicate the problem. When I started the car to leave I was able to get the sound right away and I called my SA over. He agreed but we knew were stuck unless a tech could validate it but it was already after hours. I took it in the next day, pulled into the garage, SA called over tech and Service Manager. I turned engine off for a few minutes (part of my guaranteed process to replicate the problem), started it up and demonstrated the rattle by revving to ~3300 rpm and let off the gas. rattle-rattle-rattle as the rpms came down. All three nodded their heads in unison.

This had been a problem for me for a while but have learned it is best for everyone if I am sure a problem can be reliably repeated.

thanks for sharing yoru experience. what did the dealer end up servicing in your situation?